505 Parnassus Ave. is a city within a city. There's an endless human ebb and flow, a constant whorl of motion orbiting the building's beating heart: UCSF's Children's Hospital.

Cars patiently idle at the entrance's half-moon drive as precious cargo is loaded and unloaded. Some patients arrive and depart with tubes and other medical accoutrements attached to their tiny beings, giant balloons trailing in their wake. Doctors in crisp white lab coats stroll about. Harried surgeons and nurses, still in scrubs, dash through the hallways, eyes focused on an unseen horizon. Within the main waiting room, pillows are provided to those whose waits are long -- a fitful sleep, to be sure, beneath the profusion of Babel swirling overhead.

Inside the lobby, a group of UCSF executives and department heads await the arrival of Kimberly Guilfoyle Newsom, honorary chairwoman for the hospital's Macy's Holiday Tree Lighting fund-raiser. All proceeds from the sale of the $10 lights, which illuminate the retail behemoth's 80-foot fir tree in Union Square, are donated to UCSF's Children's Center.

The city's first lady, it is well known, lives part-time in New York, where she's a Court TV anchor and legal analyst for CNN and MSNBC. But Newsom is, first, a San Franciscan. Prior to a reception announcing her participation in the campaign, she received a private tour of the 180-bed facility, renowned for its care and research.

"Hi," Newsom calls out as she walks up the sidewalk. Dressed in a sleek black business pantsuit, Newsom teases about lack of pomp in her arrival: "Very glamorous, isn't it?"

UCSF's pediatrics department, one of the first in the country, opened in 1913. It consistently ranks among the nation's top 10 hospitals. The first successful fetal surgery was performed here in 1981. Its 51-bed neonatal intensive care unit, which cares for preemies as well as newborns with congenital and hereditary conditions, is one of a kind.

But the state of American health care requires a fund-raising foundation for most hospitals. And a high-profile honorary chair.

Former 49ers great Ronnie Lott and his wife, Karen, served as last year's honorary chairs. "We look for people who not only give but give back to their community," said Roxanne Fernandes, director of patient care services. "Someone who reflects what we think we're about: service to the community."

The loudest noises within the neonatal ICU are beeping monitors and the whoosh of oxygen. The quiet is pierced by soft cries emanating from pre- and post-surgical preemies, some smaller than a loaf of bread. Tubes and wiring share space in the high-tech bassinettes with tiny teddy bears, watching over the infants like merry talismans.

"We believe the entire family is the patient," says Scurr. "We have to look out for all of them."

New mom Jacqueline Birk of Santa Rosa attends Briana, her 2-week-old daughter, who's on the road to recovery following surgery for a diaphragmatic hernia. Newsom takes a respectful peek. The proud but exhausted mom invites the first lady to hold in place the pacifier a semi-dozing Briana is enjoying. Slowly, the infant's dark eyes open. Her eyes grow wide as she focuses on the vision before her -- dark-haired like her mom but not her mom. Newsom coos softly, smiling at the baby.

"You're hired!" says Fernandes, beaming.

Aside from family issues, there's always cost, too. Briana's condition was helped by the use of nitric oxide, a new therapy crucial to healthy blood flow and blood pressure in preemies. But the treatment lacks FDA approval, and since July, the hospital has spent $1.7 million on tanks of the gas. "That's why hospitals need philanthropy," said Fernandes. "We can't say no to a child. "

Newsom is incredulous: "That's unbelievable! Yet the government has no problem saying no, and turns a proven treatment into a cost issue."

For Newsom, the decision to help UCSF was easy. "I love kids. My mother was a teacher and also worked with special-ed children. I followed in her footsteps by substitute teaching special-ed while I waited for my LSAT results. I can't stand to see children suffer or be mistreated."

Newsom also knows, too well, the trauma visited upon families struggling with a terminal illness.

"My mother (Mercedes Guilfoyle) died of leukemia. I was 10 and she was 37 -- we had a complete role reversal. It's difficult for every family member. I'll do anything I can to help sick children."

Tony Guilfoyle and his son-in-law, Mayor Gavin Newsom, each previously took a similar tour. Working his way down to the seventh floor, Guilfoyle relates the differences he's noticing when his observations are interrupted by his daughter: "Dad, this is the floor for kids with cancer." There's a hushed, unintelligible utterance as Guilfoyle makes the sign of the cross.

Robin Kramer coordinates UCSF's Pediatric Palliative Care program, a pioneering "end-of-life" care program for terminal patients. She's also the one who thought that Macy's holiday tree could do more than just delight Union Square shoppers. (Her pitch went something like, "You have a big tree, and we have a big need.")

Standing in the "comfort care suite" she points out the room's amenities: built-ins that hide medical machinery, soothing colors, wireless computers for working parents who want to be near their children, a microwave, a bed.

"In this room we will provide any aspect of a family's need," said Fernandes. Warning Laret to close his budget-conscious ears, she relates how they once flew in a medicine man from an American Indian reservation. A sand ceremony was conducted to bring closure to the mother of the dying child.

Down the hall, the group is invited into the room of Brian Cook, a 16- year-old recovering from Ewing's sarcoma.

Brian's aunt, Kacy Cook, exclaims: "You're Gavin Newsom's wife? He's such a wonderful man!" Kimberly leans out into the hallway, smiling: "We came to the right room."

Brian's parents, Jeff and Annie Cook of Sacramento, were there, too. Jeff has been sleeping at the hospital, keeping watch over his son, who has endured six rounds of chemo. Brian is pale and hairless but his build is strong. When he walks out of UCSF, it will be on the new titanium bone that replaces the knee where his tumor grew.

Downstairs, a capacity crowd waits in the cafeteria for the start of the reception. Young patients sit front and center; their parents and caregivers crouch nearby on miniature chairs. Some, like Stephanie Roberts, a teen who endured a painful liver transplant and a lengthy recovery, now radiate good health.

Behind them is a contingent of SFPD officers, including Chief Heather Fong and Gary Delagnes, president of the Police Officers Association. The men and women in blue volunteer their time during the holidays selling the Macy's tree lights.

"People say our work is difficult," said Fong. "But we salute the staff of UCSF. Their work isn't just service; it's an act of love that many of our uniformed officers and their families have had to make use of."

As cast members from the "Lion King" break into the "Circle of Life," the crowd swells. Cooks wander out from the kitchen and stand atop chairs in the back of the room. Eyes are dabbed. A young boy with the face of an old man rocks back and forth in his wheelchair.

Still abuzz from her tour, Newsom later mentions Dr. Diana Farmer, chief of pediatric surgery, and the first female fetal surgeon in the world. "When she's operating in-utero she's essentially working on two patients at once, monitoring two sets of vital signs. I just can't imagine," Newsom says. "It makes our jobs seem pretty insignificant."

Macy's Tree Lighting Ceremony is scheduled for 6 p.m. on Nov. 26 in Union Square. For more information, call (888) 689-8273 or go to www.ucsfhealth.org/tree.